[PATCH] revert msdos partitioning fix

This change from March 3rd causes the partition parsing code to ignore
partitions which have a signature byte of zero.  Turns out that more people
have such partitions than we expected, and their device numbering is coming up
wrong in post-2.6.11 kernels.

So revert the change while we think about the problem a bit more.

Cc: Andries Brouwer <Andries.Brouwer@cwi.nl>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>